Added central user credentials management

lib/api/webuntis/queries/authenticate/authenticate.dart

@@ -2,8 +2,7 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:developer';
 
-import 'package:shared_preferences/shared_preferences.dart';
-
+import '../../../../model/accountData.dart';
 import '../../webuntisApi.dart';
 import 'authenticateParams.dart';
 import 'authenticateResponse.dart';
@@ -28,12 +27,10 @@ class Authenticate extends WebuntisApi {
   static AuthenticateResponse? _lastResponse;
 
   static Future<void> createSession() async {
-    SharedPreferences preferences = await SharedPreferences.getInstance();
-
     _lastResponse = await Authenticate(
         AuthenticateParams(
-          user: preferences.getString("username")!,
-          password: preferences.getString("password")!,
+          user: AccountData().getUsername(),
+          password: AccountData().getPassword(),
         )
     ).run();
   }